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Hi all I've fitted a new gearbox into my e21 323i. It's a close ratio dogleg box but not 100% sure where it originally came from. I'm thinking an e30 as there is no connection for the speedo drive and i know they have an electronic speedo with a sensor at the diff.

I still have the original e21 box I'm thinking can i merge the mechanical speedo parts from it onto the e30 box?? Or is it impossible/not worth the effort??

Maybe it's possible to use different clocks and take the speedo from elsewhere??

I'm sure someone has came across this problem before.

Any advice or help would be much appreciated.

Imo there are a few solutions:

-if its an older version box (early E30) it may indeed have the location for the mechanical speedo plugged off. They are out there but rare.

- creating an electronic pulse by for example adding a pick up unit to one of the driveshafts, I believe a few people here have done this already like in this topic


After this you can either fit an electronic speedometer (from E30 or perhaps E28) but you need some electronics to convert the signal to the correct format.

Or buy an aftermarket converter that turns the electronic signal into a mechanical signal, which you see with older US cars a lot, for example here http://www.classicindustries.com/produc ... 1860s.html . In this way your original speedo can still be used.



- you can also get a signal generated through GPS. There are separate units that generate electronic pulses from which you can either go the E30 speedo route or use a converter to mechanical to retain your original speedo. Or get a complete GPS driven speedo: http://www.speedhut.com/gauges/GPS-Spee ... y=prodname



Want lots cheaper? Use a simple add on unit like this one or this



Or hmmmmm

Thanks for the info. I'd like to keep my original speedo or something that looks close to original as possible. I can see on the gearbox casting where the mechanical speedo connection is supposed to be I'm quite keen to open it and explore if it's a no go then that black box will be plan b